1. Field of the Invention
The present invention relates to a wire type window regulator.
2. Discussion of the Background
Examples of wire type window regulators using endless wires for raising and lowering automobile windows are previously known, such as disclosed in Japanese Utility Model Application Laid-Open Nos. 1-148486 and 2-9285.
FIG. 8 indicates a conventional wire type window regulator and FIG. 9 is an enlarged exploded view of a part thereof shown in FIG. 8. As shown in FIG. 8, an endless wire 102 is taken up and delivered by a take-up drum 106 in a drive section 104. The endless wire 102 is attached to a window glass supporting member 108, and raises and lowers the window glass supporting member 108 along a guide rail 110. A window glass (not shown) attached to the window glass supporting member 108 is thereby raised and lowered.
In the path from pulleys 112, disposed respectively at the top and bottom ends of the guide rail 110, to the drive section 104, the endless wire 102 passes through tubes 114. One end of each wire tube 114 is inserted in a guide portion 116a of a wire guide 116 of the drive section 104, and is pressed toward the releasing direction and given an arc shape by a spring 118 (see FIG. 9) compressed to less than natural length.
By giving the tube 114 an arc shape, slacking of the endless wire 102 can be avoided to prevent idle turning of the take-up drum 106.
However, in the case of a conventional wire type window regulator of this type, when the window glass supporting member 108 stops at the very top or very bottom, a large mechanical shock is imparted to guide portions 116a of the drive section 104.
For example, as the take-up drum 106 is driven and raises the window glass supporting member 108, when the window glass supporting member 108 reaches the uppermost position (i.e. window closed state), even though the window glass supporting member 108 cannot be raised further, the take-up drum 106 continues to turn. As a result, since the upper side of the endless wire 112 continues to be pulled and taken up, the tube 114 is straightened, as shown in FIG. 8.
On the other hand, since the endless wire 102 of the bottom side continues to be delivered from the take-up drum 106, force is applied to the tube 114 to have more curvature.
As a consequence, a large mechanical shock from the tubes 114 is imparted to the guide portions 116a of the drive section 104. Also, as indicated in FIG. 9, each the wire guides 116 includes a U-shaped attaching portion 117 used to attach the wire guide 116 to a housing 120 containing the take-up drum 106. The above mentioned mechanical shock may dislodge the wire guide 116. In addition, increasing the strength of the attaching portion 117 of the wire guide 116 may cause breakage of the attaching portion 122 of the housing 120.
Furthermore, since the above mentioned mechanical shock is additionally increased when an angle between one guide portion 116a and the other guide portion 116a is increased, the guide portions 116a have to be designed to have a smaller angle. As the shock is also increased when the guide portions 116a are longer, the guide portions 116a have to be designed so as to be shorter.